The present invention relates generally to mounting brackets and fixtures for mounting one object to another. More particularly, the invention relates to mounting brackets useful for mounting electrical apparatus. Still more particularly, the invention relates to an improved mounting bracket assembly for mounting surge arresters or other similarly shaped apparatus to a fixed support, such as a distribution transformer.
It is a common practice within the electrical utility industry to mount particular pieces of electrical apparatus on or adjacent to other electrical equipment. For example, surge arresters are typically mounted on the transformer or other equipment that they have been installed to protect, or mounted on some other nearby structure such as the utility pole that is supporting the transformer.
A variety of mounting assemblies have been employed to mount surge arresters and other objects to an adjacent structure. Most of these assemblies have employed a band-like hanger which is clamped around the object to be supported and then attached to a rigid bracket. The bracket, in turn, is fastened to some adjacent structure. Examples of such assemblies are disclosed in U.S. Pat. Nos. 1,911,380 and 2,472,752.
While mounting assemblies such as those disclosed in the U.S. patents referenced above have long been employed in the electrical utility industry, such mounting assemblies suffer from a number of drawbacks or deficiencies. For example, a particular weakness of the prior art designs lies in the means used to attach the hanger to the supporting bracket. It has been conventional practice to weld the band to the bracket, such as is disclosed in U.S. Pat. No. 2,472,752, or to rivet the band to the bracket as is disclosed in U.S. Pat. No. 1,911,380. Although these methods have generally proven reliable, defective welds or riveted connections can cause the mounting assembly to fail. Accordingly, the welds must be carefully performed and all such connections must be inspected during manufacture. The precision welding that is required is time consuming and, therefore, costly, and the inspection process introduces an additional step that increases the expense of manufacturing such assemblies.
In addition, the supporting brackets themselves are typically constructed from pieces of flat steel bar or plate that have been welded together into a particular shape. These weldments must likewise be carefully made and inspected. Despite such precautions, over time and with repeated use, such welded brackets tend to fatigue and may ultimately fail. Although typically made from relatively heavy gauge steel, the welded brackets have tended not to be as strong or rugged as is desirable. Failures of the bracket or of the connection between the hanger and bracket may each result in damage to expensive equipment, or may disconnect the surge arrester from the equipment it was employed to protect. In either instance, costly system outages may result.
Other problems common to conventional mounting bracket assemblies arise from the means typically employed to clamp the band about the surge arrester. In most such hangers, the band includes a pair of clamping tabs or projections which extend outwardly from the band and are employed to clamp the band securely about the surge arrester by means of a bolt that is disposed through aligned holes in the tabs. One such typical hanger is depicted in FIG. 1 of U.S. Pat. No. 3,666,992. Such outwardly extending projections consume valuable shipping space. For example, when distribution transformers designed for pole mounting are shipped with conventional arrester mounting brackets installed at the factory, the value of the space required for the outwardly extending clamping tabs may amount to several dollars per transformer. Furthermore, these clamping tabs serve as a perch for birds and other wildlife once the assembly is mounted in the field. When perched on these projections, it is not uncommon for such animals to come in contact with a live conductor or terminal. Such a wildlife perch not only creates a hazard for the wildlife, but often leads to short circuits or system faults which again may lead to power outages.
Accordingly, there remains a need in the art for a strong and durable mounting bracket assembly for surge arresters and similar apparatus. Preferably, such an assembly would include a reliable arrangement for attaching the hanger to the supporting bracket. Ideally, the bracket and the assembly as a whole would be free of welds and of outwardly extending clamping tabs, and would be simple to manufacture and install in the field with a minimum of components.
Other objects and advantages of the invention will appear from the following description.